1. Field of the Invention
The invention relates to an instrument flight training hood for preventing an aircraft pilot from viewing outside his aircraft during instrument control flight instruction, and more particularly, to such a flight hood which facilitates simulation of inflight vertigo.
2. Description of the Prior Art
In the area of inflight training, a student pilot must be trained to fly blind in bad weather. Pilots are required to have a minimum number of hours of flight instruction under simulated blind flying conditions before receiving a private or commercial license, or military rating to fly aircraft. Such training is a necessity to pilots who suddenly or inadvertently fly into bad weather conditions.
Flight training hoods have been designed to limit the wearer's field of view to only the instrument panel and immediate cockpit area. Such view limiting devices generally include elongated structures surrounding the pilot's line of vision for constriction thereof, blocking side and upper peripheral sight. Such devices are typified by U.S. Pat. No. 3,225,459 issued to L. L. Wilstein on Dec. 28, 1965 and U.S. Pat. No. 3,392,461 issued to A. Jenison on July 16, 1968.
Such flight hoods do not totally enclose or mask the wearer's line of vision in order to provide a safety factor which insures that the pilot can direct his vision outside the craft in the case of an emergency. However, to accomplish this factor, the hood's elongated structure extending in front of the operator's face becomes awkward and clumsy during flight and may cause eye straining or neck fatigue to support such apparatus. Also, the instructor must depend upon the wearer's trustworthiness during a testing and learning situation to purposefully keep his head substantially level.
Also, where the pilot inadvertently views outside of the aircraft, he would transition to VFR (visual flight rules) and must immediately transition back to IFR (instrument flight rules) as he looks back into the aircraft. This causes a disorientation to the pilot, promoting a time delay factor due to transition reorientation time. This psychological-type problem occurs with inadvertent viewing using the above-mentioned prior art devices.
Lens fogging-type devices including liquid crystals and other similar means have not been considered nor utilized in the flight hood art because of a lack of mode of operation therein and because of the previously mentioned safety factor. Although such lens devices have been utilized in helmet-type gear, see for example U.S. Pat. No. 3,873,804 issued to M. Gordan on Mar. 25, 1974 and U.S. Pat. No. 3,409,909 issued to D. D. Scott et al. on Nov. 12, 1968, the functioning of such devices are not compliant to the flight training hood art. Such devices are responsive to a bright flash of light that occurs during wearer viewing. However, in the flight training environment all stimuli including the ambient light in the cockpit are constant, having no apparent abrupt stimulus occurring at the time the desired fogging should take place.
Therefore, it would be highly desirable to provide a flight training hood having the ease and convenience of an unawkward structure including the quickness of an automatic lens system in which the lens would instantaneously operate in relation to the wearer's positioning of his line of vision.